1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * The Internet Protocol (IP) output module. 7 * 8 * Authors: Ross Biro 9 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 10 * Donald Becker, <becker@super.org> 11 * Alan Cox, <Alan.Cox@linux.org> 12 * Richard Underwood 13 * Stefan Becker, <stefanb@yello.ping.de> 14 * Jorge Cwik, <jorge@laser.satlink.net> 15 * Arnt Gulbrandsen, <agulbra@nvg.unit.no> 16 * Hirokazu Takahashi, <taka@valinux.co.jp> 17 * 18 * See ip_input.c for original log 19 * 20 * Fixes: 21 * Alan Cox : Missing nonblock feature in ip_build_xmit. 22 * Mike Kilburn : htons() missing in ip_build_xmit. 23 * Bradford Johnson: Fix faulty handling of some frames when 24 * no route is found. 25 * Alexander Demenshin: Missing sk/skb free in ip_queue_xmit 26 * (in case if packet not accepted by 27 * output firewall rules) 28 * Mike McLagan : Routing by source 29 * Alexey Kuznetsov: use new route cache 30 * Andi Kleen: Fix broken PMTU recovery and remove 31 * some redundant tests. 32 * Vitaly E. Lavrov : Transparent proxy revived after year coma. 33 * Andi Kleen : Replace ip_reply with ip_send_reply. 34 * Andi Kleen : Split fast and slow ip_build_xmit path 35 * for decreased register pressure on x86 36 * and more readibility. 37 * Marc Boucher : When call_out_firewall returns FW_QUEUE, 38 * silently drop skb instead of failing with -EPERM. 39 * Detlev Wengorz : Copy protocol for fragments. 40 * Hirokazu Takahashi: HW checksumming for outgoing UDP 41 * datagrams. 42 * Hirokazu Takahashi: sendfile() on UDP works now. 43 */ 44 45 #include <asm/uaccess.h> 46 #include <linux/module.h> 47 #include <linux/types.h> 48 #include <linux/kernel.h> 49 #include <linux/mm.h> 50 #include <linux/string.h> 51 #include <linux/errno.h> 52 #include <linux/highmem.h> 53 #include <linux/slab.h> 54 55 #include <linux/socket.h> 56 #include <linux/sockios.h> 57 #include <linux/in.h> 58 #include <linux/inet.h> 59 #include <linux/netdevice.h> 60 #include <linux/etherdevice.h> 61 #include <linux/proc_fs.h> 62 #include <linux/stat.h> 63 #include <linux/init.h> 64 65 #include <net/snmp.h> 66 #include <net/ip.h> 67 #include <net/protocol.h> 68 #include <net/route.h> 69 #include <net/xfrm.h> 70 #include <linux/skbuff.h> 71 #include <net/sock.h> 72 #include <net/arp.h> 73 #include <net/icmp.h> 74 #include <net/checksum.h> 75 #include <net/inetpeer.h> 76 #include <linux/igmp.h> 77 #include <linux/netfilter_ipv4.h> 78 #include <linux/netfilter_bridge.h> 79 #include <linux/mroute.h> 80 #include <linux/netlink.h> 81 #include <linux/tcp.h> 82 83 int sysctl_ip_default_ttl __read_mostly = IPDEFTTL; 84 EXPORT_SYMBOL(sysctl_ip_default_ttl); 85 86 /* Generate a checksum for an outgoing IP datagram. */ 87 __inline__ void ip_send_check(struct iphdr *iph) 88 { 89 iph->check = 0; 90 iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl); 91 } 92 EXPORT_SYMBOL(ip_send_check); 93 94 int __ip_local_out(struct sk_buff *skb) 95 { 96 struct iphdr *iph = ip_hdr(skb); 97 98 iph->tot_len = htons(skb->len); 99 ip_send_check(iph); 100 return nf_hook(NFPROTO_IPV4, NF_INET_LOCAL_OUT, skb, NULL, 101 skb_dst(skb)->dev, dst_output); 102 } 103 104 int ip_local_out(struct sk_buff *skb) 105 { 106 int err; 107 108 err = __ip_local_out(skb); 109 if (likely(err == 1)) 110 err = dst_output(skb); 111 112 return err; 113 } 114 EXPORT_SYMBOL_GPL(ip_local_out); 115 116 static inline int ip_select_ttl(struct inet_sock *inet, struct dst_entry *dst) 117 { 118 int ttl = inet->uc_ttl; 119 120 if (ttl < 0) 121 ttl = ip4_dst_hoplimit(dst); 122 return ttl; 123 } 124 125 /* 126 * Add an ip header to a skbuff and send it out. 127 * 128 */ 129 int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk, 130 __be32 saddr, __be32 daddr, struct ip_options_rcu *opt) 131 { 132 struct inet_sock *inet = inet_sk(sk); 133 struct rtable *rt = skb_rtable(skb); 134 struct iphdr *iph; 135 136 /* Build the IP header. */ 137 skb_push(skb, sizeof(struct iphdr) + (opt ? opt->opt.optlen : 0)); 138 skb_reset_network_header(skb); 139 iph = ip_hdr(skb); 140 iph->version = 4; 141 iph->ihl = 5; 142 iph->tos = inet->tos; 143 if (ip_dont_fragment(sk, &rt->dst)) 144 iph->frag_off = htons(IP_DF); 145 else 146 iph->frag_off = 0; 147 iph->ttl = ip_select_ttl(inet, &rt->dst); 148 iph->daddr = (opt && opt->opt.srr ? opt->opt.faddr : daddr); 149 iph->saddr = saddr; 150 iph->protocol = sk->sk_protocol; 151 ip_select_ident(iph, &rt->dst, sk); 152 153 if (opt && opt->opt.optlen) { 154 iph->ihl += opt->opt.optlen>>2; 155 ip_options_build(skb, &opt->opt, daddr, rt, 0); 156 } 157 158 skb->priority = sk->sk_priority; 159 skb->mark = sk->sk_mark; 160 161 /* Send it out. */ 162 return ip_local_out(skb); 163 } 164 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt); 165 166 static inline int ip_finish_output2(struct sk_buff *skb) 167 { 168 struct dst_entry *dst = skb_dst(skb); 169 struct rtable *rt = (struct rtable *)dst; 170 struct net_device *dev = dst->dev; 171 unsigned int hh_len = LL_RESERVED_SPACE(dev); 172 struct neighbour *neigh; 173 u32 nexthop; 174 175 if (rt->rt_type == RTN_MULTICAST) { 176 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTMCAST, skb->len); 177 } else if (rt->rt_type == RTN_BROADCAST) 178 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUTBCAST, skb->len); 179 180 /* Be paranoid, rather than too clever. */ 181 if (unlikely(skb_headroom(skb) < hh_len && dev->header_ops)) { 182 struct sk_buff *skb2; 183 184 skb2 = skb_realloc_headroom(skb, LL_RESERVED_SPACE(dev)); 185 if (skb2 == NULL) { 186 kfree_skb(skb); 187 return -ENOMEM; 188 } 189 if (skb->sk) 190 skb_set_owner_w(skb2, skb->sk); 191 consume_skb(skb); 192 skb = skb2; 193 } 194 195 rcu_read_lock_bh(); 196 nexthop = rt->rt_gateway ? rt->rt_gateway : ip_hdr(skb)->daddr; 197 neigh = __ipv4_neigh_lookup_noref(dev, nexthop); 198 if (unlikely(!neigh)) 199 neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); 200 if (!IS_ERR(neigh)) { 201 int res = dst_neigh_output(dst, neigh, skb); 202 203 rcu_read_unlock_bh(); 204 return res; 205 } 206 rcu_read_unlock_bh(); 207 208 net_dbg_ratelimited("%s: No header cache and no neighbour!\n", 209 __func__); 210 kfree_skb(skb); 211 return -EINVAL; 212 } 213 214 static inline int ip_skb_dst_mtu(struct sk_buff *skb) 215 { 216 struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL; 217 218 return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ? 219 skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb)); 220 } 221 222 static int ip_finish_output(struct sk_buff *skb) 223 { 224 #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) 225 /* Policy lookup after SNAT yielded a new policy */ 226 if (skb_dst(skb)->xfrm != NULL) { 227 IPCB(skb)->flags |= IPSKB_REROUTED; 228 return dst_output(skb); 229 } 230 #endif 231 if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb)) 232 return ip_fragment(skb, ip_finish_output2); 233 else 234 return ip_finish_output2(skb); 235 } 236 237 int ip_mc_output(struct sk_buff *skb) 238 { 239 struct sock *sk = skb->sk; 240 struct rtable *rt = skb_rtable(skb); 241 struct net_device *dev = rt->dst.dev; 242 243 /* 244 * If the indicated interface is up and running, send the packet. 245 */ 246 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 247 248 skb->dev = dev; 249 skb->protocol = htons(ETH_P_IP); 250 251 /* 252 * Multicasts are looped back for other local users 253 */ 254 255 if (rt->rt_flags&RTCF_MULTICAST) { 256 if (sk_mc_loop(sk) 257 #ifdef CONFIG_IP_MROUTE 258 /* Small optimization: do not loopback not local frames, 259 which returned after forwarding; they will be dropped 260 by ip_mr_input in any case. 261 Note, that local frames are looped back to be delivered 262 to local recipients. 263 264 This check is duplicated in ip_mr_input at the moment. 265 */ 266 && 267 ((rt->rt_flags & RTCF_LOCAL) || 268 !(IPCB(skb)->flags & IPSKB_FORWARDED)) 269 #endif 270 ) { 271 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 272 if (newskb) 273 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, 274 newskb, NULL, newskb->dev, 275 dev_loopback_xmit); 276 } 277 278 /* Multicasts with ttl 0 must not go beyond the host */ 279 280 if (ip_hdr(skb)->ttl == 0) { 281 kfree_skb(skb); 282 return 0; 283 } 284 } 285 286 if (rt->rt_flags&RTCF_BROADCAST) { 287 struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC); 288 if (newskb) 289 NF_HOOK(NFPROTO_IPV4, NF_INET_POST_ROUTING, newskb, 290 NULL, newskb->dev, dev_loopback_xmit); 291 } 292 293 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, 294 skb->dev, ip_finish_output, 295 !(IPCB(skb)->flags & IPSKB_REROUTED)); 296 } 297 298 int ip_output(struct sk_buff *skb) 299 { 300 struct net_device *dev = skb_dst(skb)->dev; 301 302 IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len); 303 304 skb->dev = dev; 305 skb->protocol = htons(ETH_P_IP); 306 307 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dev, 308 ip_finish_output, 309 !(IPCB(skb)->flags & IPSKB_REROUTED)); 310 } 311 312 /* 313 * copy saddr and daddr, possibly using 64bit load/stores 314 * Equivalent to : 315 * iph->saddr = fl4->saddr; 316 * iph->daddr = fl4->daddr; 317 */ 318 static void ip_copy_addrs(struct iphdr *iph, const struct flowi4 *fl4) 319 { 320 BUILD_BUG_ON(offsetof(typeof(*fl4), daddr) != 321 offsetof(typeof(*fl4), saddr) + sizeof(fl4->saddr)); 322 memcpy(&iph->saddr, &fl4->saddr, 323 sizeof(fl4->saddr) + sizeof(fl4->daddr)); 324 } 325 326 int ip_queue_xmit(struct sk_buff *skb, struct flowi *fl) 327 { 328 struct sock *sk = skb->sk; 329 struct inet_sock *inet = inet_sk(sk); 330 struct ip_options_rcu *inet_opt; 331 struct flowi4 *fl4; 332 struct rtable *rt; 333 struct iphdr *iph; 334 int res; 335 336 /* Skip all of this if the packet is already routed, 337 * f.e. by something like SCTP. 338 */ 339 rcu_read_lock(); 340 inet_opt = rcu_dereference(inet->inet_opt); 341 fl4 = &fl->u.ip4; 342 rt = skb_rtable(skb); 343 if (rt != NULL) 344 goto packet_routed; 345 346 /* Make sure we can route this packet. */ 347 rt = (struct rtable *)__sk_dst_check(sk, 0); 348 if (rt == NULL) { 349 __be32 daddr; 350 351 /* Use correct destination address if we have options. */ 352 daddr = inet->inet_daddr; 353 if (inet_opt && inet_opt->opt.srr) 354 daddr = inet_opt->opt.faddr; 355 356 /* If this fails, retransmit mechanism of transport layer will 357 * keep trying until route appears or the connection times 358 * itself out. 359 */ 360 rt = ip_route_output_ports(sock_net(sk), fl4, sk, 361 daddr, inet->inet_saddr, 362 inet->inet_dport, 363 inet->inet_sport, 364 sk->sk_protocol, 365 RT_CONN_FLAGS(sk), 366 sk->sk_bound_dev_if); 367 if (IS_ERR(rt)) 368 goto no_route; 369 sk_setup_caps(sk, &rt->dst); 370 } 371 skb_dst_set_noref(skb, &rt->dst); 372 373 packet_routed: 374 if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_gateway) 375 goto no_route; 376 377 /* OK, we know where to send it, allocate and build IP header. */ 378 skb_push(skb, sizeof(struct iphdr) + (inet_opt ? inet_opt->opt.optlen : 0)); 379 skb_reset_network_header(skb); 380 iph = ip_hdr(skb); 381 *((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff)); 382 if (ip_dont_fragment(sk, &rt->dst) && !skb->local_df) 383 iph->frag_off = htons(IP_DF); 384 else 385 iph->frag_off = 0; 386 iph->ttl = ip_select_ttl(inet, &rt->dst); 387 iph->protocol = sk->sk_protocol; 388 ip_copy_addrs(iph, fl4); 389 390 /* Transport layer set skb->h.foo itself. */ 391 392 if (inet_opt && inet_opt->opt.optlen) { 393 iph->ihl += inet_opt->opt.optlen >> 2; 394 ip_options_build(skb, &inet_opt->opt, inet->inet_daddr, rt, 0); 395 } 396 397 ip_select_ident_more(iph, &rt->dst, sk, 398 (skb_shinfo(skb)->gso_segs ?: 1) - 1); 399 400 skb->priority = sk->sk_priority; 401 skb->mark = sk->sk_mark; 402 403 res = ip_local_out(skb); 404 rcu_read_unlock(); 405 return res; 406 407 no_route: 408 rcu_read_unlock(); 409 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES); 410 kfree_skb(skb); 411 return -EHOSTUNREACH; 412 } 413 EXPORT_SYMBOL(ip_queue_xmit); 414 415 416 static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) 417 { 418 to->pkt_type = from->pkt_type; 419 to->priority = from->priority; 420 to->protocol = from->protocol; 421 skb_dst_drop(to); 422 skb_dst_copy(to, from); 423 to->dev = from->dev; 424 to->mark = from->mark; 425 426 /* Copy the flags to each fragment. */ 427 IPCB(to)->flags = IPCB(from)->flags; 428 429 #ifdef CONFIG_NET_SCHED 430 to->tc_index = from->tc_index; 431 #endif 432 nf_copy(to, from); 433 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \ 434 defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE) 435 to->nf_trace = from->nf_trace; 436 #endif 437 #if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE) 438 to->ipvs_property = from->ipvs_property; 439 #endif 440 skb_copy_secmark(to, from); 441 } 442 443 /* 444 * This IP datagram is too large to be sent in one piece. Break it up into 445 * smaller pieces (each of size equal to IP header plus 446 * a block of the data of the original IP data part) that will yet fit in a 447 * single device frame, and queue such a frame for sending. 448 */ 449 450 int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) 451 { 452 struct iphdr *iph; 453 int ptr; 454 struct net_device *dev; 455 struct sk_buff *skb2; 456 unsigned int mtu, hlen, left, len, ll_rs; 457 int offset; 458 __be16 not_last_frag; 459 struct rtable *rt = skb_rtable(skb); 460 int err = 0; 461 462 dev = rt->dst.dev; 463 464 /* 465 * Point into the IP datagram header. 466 */ 467 468 iph = ip_hdr(skb); 469 470 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) || 471 (IPCB(skb)->frag_max_size && 472 IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) { 473 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 474 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, 475 htonl(ip_skb_dst_mtu(skb))); 476 kfree_skb(skb); 477 return -EMSGSIZE; 478 } 479 480 /* 481 * Setup starting values. 482 */ 483 484 hlen = iph->ihl * 4; 485 mtu = dst_mtu(&rt->dst) - hlen; /* Size of data space */ 486 #ifdef CONFIG_BRIDGE_NETFILTER 487 if (skb->nf_bridge) 488 mtu -= nf_bridge_mtu_reduction(skb); 489 #endif 490 IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; 491 492 /* When frag_list is given, use it. First, check its validity: 493 * some transformers could create wrong frag_list or break existing 494 * one, it is not prohibited. In this case fall back to copying. 495 * 496 * LATER: this step can be merged to real generation of fragments, 497 * we can switch to copy when see the first bad fragment. 498 */ 499 if (skb_has_frag_list(skb)) { 500 struct sk_buff *frag, *frag2; 501 int first_len = skb_pagelen(skb); 502 503 if (first_len - hlen > mtu || 504 ((first_len - hlen) & 7) || 505 ip_is_fragment(iph) || 506 skb_cloned(skb)) 507 goto slow_path; 508 509 skb_walk_frags(skb, frag) { 510 /* Correct geometry. */ 511 if (frag->len > mtu || 512 ((frag->len & 7) && frag->next) || 513 skb_headroom(frag) < hlen) 514 goto slow_path_clean; 515 516 /* Partially cloned skb? */ 517 if (skb_shared(frag)) 518 goto slow_path_clean; 519 520 BUG_ON(frag->sk); 521 if (skb->sk) { 522 frag->sk = skb->sk; 523 frag->destructor = sock_wfree; 524 } 525 skb->truesize -= frag->truesize; 526 } 527 528 /* Everything is OK. Generate! */ 529 530 err = 0; 531 offset = 0; 532 frag = skb_shinfo(skb)->frag_list; 533 skb_frag_list_init(skb); 534 skb->data_len = first_len - skb_headlen(skb); 535 skb->len = first_len; 536 iph->tot_len = htons(first_len); 537 iph->frag_off = htons(IP_MF); 538 ip_send_check(iph); 539 540 for (;;) { 541 /* Prepare header of the next frame, 542 * before previous one went down. */ 543 if (frag) { 544 frag->ip_summed = CHECKSUM_NONE; 545 skb_reset_transport_header(frag); 546 __skb_push(frag, hlen); 547 skb_reset_network_header(frag); 548 memcpy(skb_network_header(frag), iph, hlen); 549 iph = ip_hdr(frag); 550 iph->tot_len = htons(frag->len); 551 ip_copy_metadata(frag, skb); 552 if (offset == 0) 553 ip_options_fragment(frag); 554 offset += skb->len - hlen; 555 iph->frag_off = htons(offset>>3); 556 if (frag->next != NULL) 557 iph->frag_off |= htons(IP_MF); 558 /* Ready, complete checksum */ 559 ip_send_check(iph); 560 } 561 562 err = output(skb); 563 564 if (!err) 565 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 566 if (err || !frag) 567 break; 568 569 skb = frag; 570 frag = skb->next; 571 skb->next = NULL; 572 } 573 574 if (err == 0) { 575 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 576 return 0; 577 } 578 579 while (frag) { 580 skb = frag->next; 581 kfree_skb(frag); 582 frag = skb; 583 } 584 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 585 return err; 586 587 slow_path_clean: 588 skb_walk_frags(skb, frag2) { 589 if (frag2 == frag) 590 break; 591 frag2->sk = NULL; 592 frag2->destructor = NULL; 593 skb->truesize += frag2->truesize; 594 } 595 } 596 597 slow_path: 598 left = skb->len - hlen; /* Space per frame */ 599 ptr = hlen; /* Where to start from */ 600 601 /* for bridged IP traffic encapsulated inside f.e. a vlan header, 602 * we need to make room for the encapsulating header 603 */ 604 ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); 605 606 /* 607 * Fragment the datagram. 608 */ 609 610 offset = (ntohs(iph->frag_off) & IP_OFFSET) << 3; 611 not_last_frag = iph->frag_off & htons(IP_MF); 612 613 /* 614 * Keep copying data until we run out. 615 */ 616 617 while (left > 0) { 618 len = left; 619 /* IF: it doesn't fit, use 'mtu' - the data space left */ 620 if (len > mtu) 621 len = mtu; 622 /* IF: we are not sending up to and including the packet end 623 then align the next start on an eight byte boundary */ 624 if (len < left) { 625 len &= ~7; 626 } 627 /* 628 * Allocate buffer. 629 */ 630 631 if ((skb2 = alloc_skb(len+hlen+ll_rs, GFP_ATOMIC)) == NULL) { 632 NETDEBUG(KERN_INFO "IP: frag: no memory for new fragment!\n"); 633 err = -ENOMEM; 634 goto fail; 635 } 636 637 /* 638 * Set up data on packet 639 */ 640 641 ip_copy_metadata(skb2, skb); 642 skb_reserve(skb2, ll_rs); 643 skb_put(skb2, len + hlen); 644 skb_reset_network_header(skb2); 645 skb2->transport_header = skb2->network_header + hlen; 646 647 /* 648 * Charge the memory for the fragment to any owner 649 * it might possess 650 */ 651 652 if (skb->sk) 653 skb_set_owner_w(skb2, skb->sk); 654 655 /* 656 * Copy the packet header into the new buffer. 657 */ 658 659 skb_copy_from_linear_data(skb, skb_network_header(skb2), hlen); 660 661 /* 662 * Copy a block of the IP datagram. 663 */ 664 if (skb_copy_bits(skb, ptr, skb_transport_header(skb2), len)) 665 BUG(); 666 left -= len; 667 668 /* 669 * Fill in the new header fields. 670 */ 671 iph = ip_hdr(skb2); 672 iph->frag_off = htons((offset >> 3)); 673 674 /* ANK: dirty, but effective trick. Upgrade options only if 675 * the segment to be fragmented was THE FIRST (otherwise, 676 * options are already fixed) and make it ONCE 677 * on the initial skb, so that all the following fragments 678 * will inherit fixed options. 679 */ 680 if (offset == 0) 681 ip_options_fragment(skb); 682 683 /* 684 * Added AC : If we are fragmenting a fragment that's not the 685 * last fragment then keep MF on each bit 686 */ 687 if (left > 0 || not_last_frag) 688 iph->frag_off |= htons(IP_MF); 689 ptr += len; 690 offset += len; 691 692 /* 693 * Put this fragment into the sending queue. 694 */ 695 iph->tot_len = htons(len + hlen); 696 697 ip_send_check(iph); 698 699 err = output(skb2); 700 if (err) 701 goto fail; 702 703 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); 704 } 705 consume_skb(skb); 706 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); 707 return err; 708 709 fail: 710 kfree_skb(skb); 711 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); 712 return err; 713 } 714 EXPORT_SYMBOL(ip_fragment); 715 716 int 717 ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 718 { 719 struct iovec *iov = from; 720 721 if (skb->ip_summed == CHECKSUM_PARTIAL) { 722 if (memcpy_fromiovecend(to, iov, offset, len) < 0) 723 return -EFAULT; 724 } else { 725 __wsum csum = 0; 726 if (csum_partial_copy_fromiovecend(to, iov, offset, len, &csum) < 0) 727 return -EFAULT; 728 skb->csum = csum_block_add(skb->csum, csum, odd); 729 } 730 return 0; 731 } 732 EXPORT_SYMBOL(ip_generic_getfrag); 733 734 static inline __wsum 735 csum_page(struct page *page, int offset, int copy) 736 { 737 char *kaddr; 738 __wsum csum; 739 kaddr = kmap(page); 740 csum = csum_partial(kaddr + offset, copy, 0); 741 kunmap(page); 742 return csum; 743 } 744 745 static inline int ip_ufo_append_data(struct sock *sk, 746 struct sk_buff_head *queue, 747 int getfrag(void *from, char *to, int offset, int len, 748 int odd, struct sk_buff *skb), 749 void *from, int length, int hh_len, int fragheaderlen, 750 int transhdrlen, int maxfraglen, unsigned int flags) 751 { 752 struct sk_buff *skb; 753 int err; 754 755 /* There is support for UDP fragmentation offload by network 756 * device, so create one single skb packet containing complete 757 * udp datagram 758 */ 759 if ((skb = skb_peek_tail(queue)) == NULL) { 760 skb = sock_alloc_send_skb(sk, 761 hh_len + fragheaderlen + transhdrlen + 20, 762 (flags & MSG_DONTWAIT), &err); 763 764 if (skb == NULL) 765 return err; 766 767 /* reserve space for Hardware header */ 768 skb_reserve(skb, hh_len); 769 770 /* create space for UDP/IP header */ 771 skb_put(skb, fragheaderlen + transhdrlen); 772 773 /* initialize network header pointer */ 774 skb_reset_network_header(skb); 775 776 /* initialize protocol header pointer */ 777 skb->transport_header = skb->network_header + fragheaderlen; 778 779 skb->ip_summed = CHECKSUM_PARTIAL; 780 skb->csum = 0; 781 782 /* specify the length of each IP datagram fragment */ 783 skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen; 784 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 785 __skb_queue_tail(queue, skb); 786 } 787 788 return skb_append_datato_frags(sk, skb, getfrag, from, 789 (length - transhdrlen)); 790 } 791 792 static int __ip_append_data(struct sock *sk, 793 struct flowi4 *fl4, 794 struct sk_buff_head *queue, 795 struct inet_cork *cork, 796 int getfrag(void *from, char *to, int offset, 797 int len, int odd, struct sk_buff *skb), 798 void *from, int length, int transhdrlen, 799 unsigned int flags) 800 { 801 struct inet_sock *inet = inet_sk(sk); 802 struct sk_buff *skb; 803 804 struct ip_options *opt = cork->opt; 805 int hh_len; 806 int exthdrlen; 807 int mtu; 808 int copy; 809 int err; 810 int offset = 0; 811 unsigned int maxfraglen, fragheaderlen; 812 int csummode = CHECKSUM_NONE; 813 struct rtable *rt = (struct rtable *)cork->dst; 814 815 skb = skb_peek_tail(queue); 816 817 exthdrlen = !skb ? rt->dst.header_len : 0; 818 mtu = cork->fragsize; 819 820 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 821 822 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 823 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 824 825 if (cork->length + length > 0xFFFF - fragheaderlen) { 826 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, 827 mtu-exthdrlen); 828 return -EMSGSIZE; 829 } 830 831 /* 832 * transhdrlen > 0 means that this is the first fragment and we wish 833 * it won't be fragmented in the future. 834 */ 835 if (transhdrlen && 836 length + fragheaderlen <= mtu && 837 rt->dst.dev->features & NETIF_F_V4_CSUM && 838 !exthdrlen) 839 csummode = CHECKSUM_PARTIAL; 840 841 cork->length += length; 842 if (((length > mtu) || (skb && skb_is_gso(skb))) && 843 (sk->sk_protocol == IPPROTO_UDP) && 844 (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len) { 845 err = ip_ufo_append_data(sk, queue, getfrag, from, length, 846 hh_len, fragheaderlen, transhdrlen, 847 maxfraglen, flags); 848 if (err) 849 goto error; 850 return 0; 851 } 852 853 /* So, what's going on in the loop below? 854 * 855 * We use calculated fragment length to generate chained skb, 856 * each of segments is IP fragment ready for sending to network after 857 * adding appropriate IP header. 858 */ 859 860 if (!skb) 861 goto alloc_new_skb; 862 863 while (length > 0) { 864 /* Check if the remaining data fits into current packet. */ 865 copy = mtu - skb->len; 866 if (copy < length) 867 copy = maxfraglen - skb->len; 868 if (copy <= 0) { 869 char *data; 870 unsigned int datalen; 871 unsigned int fraglen; 872 unsigned int fraggap; 873 unsigned int alloclen; 874 struct sk_buff *skb_prev; 875 alloc_new_skb: 876 skb_prev = skb; 877 if (skb_prev) 878 fraggap = skb_prev->len - maxfraglen; 879 else 880 fraggap = 0; 881 882 /* 883 * If remaining data exceeds the mtu, 884 * we know we need more fragment(s). 885 */ 886 datalen = length + fraggap; 887 if (datalen > mtu - fragheaderlen) 888 datalen = maxfraglen - fragheaderlen; 889 fraglen = datalen + fragheaderlen; 890 891 if ((flags & MSG_MORE) && 892 !(rt->dst.dev->features&NETIF_F_SG)) 893 alloclen = mtu; 894 else 895 alloclen = fraglen; 896 897 alloclen += exthdrlen; 898 899 /* The last fragment gets additional space at tail. 900 * Note, with MSG_MORE we overallocate on fragments, 901 * because we have no idea what fragment will be 902 * the last. 903 */ 904 if (datalen == length + fraggap) 905 alloclen += rt->dst.trailer_len; 906 907 if (transhdrlen) { 908 skb = sock_alloc_send_skb(sk, 909 alloclen + hh_len + 15, 910 (flags & MSG_DONTWAIT), &err); 911 } else { 912 skb = NULL; 913 if (atomic_read(&sk->sk_wmem_alloc) <= 914 2 * sk->sk_sndbuf) 915 skb = sock_wmalloc(sk, 916 alloclen + hh_len + 15, 1, 917 sk->sk_allocation); 918 if (unlikely(skb == NULL)) 919 err = -ENOBUFS; 920 else 921 /* only the initial fragment is 922 time stamped */ 923 cork->tx_flags = 0; 924 } 925 if (skb == NULL) 926 goto error; 927 928 /* 929 * Fill in the control structures 930 */ 931 skb->ip_summed = csummode; 932 skb->csum = 0; 933 skb_reserve(skb, hh_len); 934 skb_shinfo(skb)->tx_flags = cork->tx_flags; 935 936 /* 937 * Find where to start putting bytes. 938 */ 939 data = skb_put(skb, fraglen + exthdrlen); 940 skb_set_network_header(skb, exthdrlen); 941 skb->transport_header = (skb->network_header + 942 fragheaderlen); 943 data += fragheaderlen + exthdrlen; 944 945 if (fraggap) { 946 skb->csum = skb_copy_and_csum_bits( 947 skb_prev, maxfraglen, 948 data + transhdrlen, fraggap, 0); 949 skb_prev->csum = csum_sub(skb_prev->csum, 950 skb->csum); 951 data += fraggap; 952 pskb_trim_unique(skb_prev, maxfraglen); 953 } 954 955 copy = datalen - transhdrlen - fraggap; 956 if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { 957 err = -EFAULT; 958 kfree_skb(skb); 959 goto error; 960 } 961 962 offset += copy; 963 length -= datalen - fraggap; 964 transhdrlen = 0; 965 exthdrlen = 0; 966 csummode = CHECKSUM_NONE; 967 968 /* 969 * Put the packet on the pending queue. 970 */ 971 __skb_queue_tail(queue, skb); 972 continue; 973 } 974 975 if (copy > length) 976 copy = length; 977 978 if (!(rt->dst.dev->features&NETIF_F_SG)) { 979 unsigned int off; 980 981 off = skb->len; 982 if (getfrag(from, skb_put(skb, copy), 983 offset, copy, off, skb) < 0) { 984 __skb_trim(skb, off); 985 err = -EFAULT; 986 goto error; 987 } 988 } else { 989 int i = skb_shinfo(skb)->nr_frags; 990 skb_frag_t *frag = &skb_shinfo(skb)->frags[i-1]; 991 struct page *page = cork->page; 992 int off = cork->off; 993 unsigned int left; 994 995 if (page && (left = PAGE_SIZE - off) > 0) { 996 if (copy >= left) 997 copy = left; 998 if (page != skb_frag_page(frag)) { 999 if (i == MAX_SKB_FRAGS) { 1000 err = -EMSGSIZE; 1001 goto error; 1002 } 1003 skb_fill_page_desc(skb, i, page, off, 0); 1004 skb_frag_ref(skb, i); 1005 frag = &skb_shinfo(skb)->frags[i]; 1006 } 1007 } else if (i < MAX_SKB_FRAGS) { 1008 if (copy > PAGE_SIZE) 1009 copy = PAGE_SIZE; 1010 page = alloc_pages(sk->sk_allocation, 0); 1011 if (page == NULL) { 1012 err = -ENOMEM; 1013 goto error; 1014 } 1015 cork->page = page; 1016 cork->off = 0; 1017 1018 skb_fill_page_desc(skb, i, page, 0, 0); 1019 frag = &skb_shinfo(skb)->frags[i]; 1020 } else { 1021 err = -EMSGSIZE; 1022 goto error; 1023 } 1024 if (getfrag(from, skb_frag_address(frag)+skb_frag_size(frag), 1025 offset, copy, skb->len, skb) < 0) { 1026 err = -EFAULT; 1027 goto error; 1028 } 1029 cork->off += copy; 1030 skb_frag_size_add(frag, copy); 1031 skb->len += copy; 1032 skb->data_len += copy; 1033 skb->truesize += copy; 1034 atomic_add(copy, &sk->sk_wmem_alloc); 1035 } 1036 offset += copy; 1037 length -= copy; 1038 } 1039 1040 return 0; 1041 1042 error: 1043 cork->length -= length; 1044 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1045 return err; 1046 } 1047 1048 static int ip_setup_cork(struct sock *sk, struct inet_cork *cork, 1049 struct ipcm_cookie *ipc, struct rtable **rtp) 1050 { 1051 struct inet_sock *inet = inet_sk(sk); 1052 struct ip_options_rcu *opt; 1053 struct rtable *rt; 1054 1055 /* 1056 * setup for corking. 1057 */ 1058 opt = ipc->opt; 1059 if (opt) { 1060 if (cork->opt == NULL) { 1061 cork->opt = kmalloc(sizeof(struct ip_options) + 40, 1062 sk->sk_allocation); 1063 if (unlikely(cork->opt == NULL)) 1064 return -ENOBUFS; 1065 } 1066 memcpy(cork->opt, &opt->opt, sizeof(struct ip_options) + opt->opt.optlen); 1067 cork->flags |= IPCORK_OPT; 1068 cork->addr = ipc->addr; 1069 } 1070 rt = *rtp; 1071 if (unlikely(!rt)) 1072 return -EFAULT; 1073 /* 1074 * We steal reference to this route, caller should not release it 1075 */ 1076 *rtp = NULL; 1077 cork->fragsize = inet->pmtudisc == IP_PMTUDISC_PROBE ? 1078 rt->dst.dev->mtu : dst_mtu(&rt->dst); 1079 cork->dst = &rt->dst; 1080 cork->length = 0; 1081 cork->tx_flags = ipc->tx_flags; 1082 cork->page = NULL; 1083 cork->off = 0; 1084 1085 return 0; 1086 } 1087 1088 /* 1089 * ip_append_data() and ip_append_page() can make one large IP datagram 1090 * from many pieces of data. Each pieces will be holded on the socket 1091 * until ip_push_pending_frames() is called. Each piece can be a page 1092 * or non-page data. 1093 * 1094 * Not only UDP, other transport protocols - e.g. raw sockets - can use 1095 * this interface potentially. 1096 * 1097 * LATER: length must be adjusted by pad at tail, when it is required. 1098 */ 1099 int ip_append_data(struct sock *sk, struct flowi4 *fl4, 1100 int getfrag(void *from, char *to, int offset, int len, 1101 int odd, struct sk_buff *skb), 1102 void *from, int length, int transhdrlen, 1103 struct ipcm_cookie *ipc, struct rtable **rtp, 1104 unsigned int flags) 1105 { 1106 struct inet_sock *inet = inet_sk(sk); 1107 int err; 1108 1109 if (flags&MSG_PROBE) 1110 return 0; 1111 1112 if (skb_queue_empty(&sk->sk_write_queue)) { 1113 err = ip_setup_cork(sk, &inet->cork.base, ipc, rtp); 1114 if (err) 1115 return err; 1116 } else { 1117 transhdrlen = 0; 1118 } 1119 1120 return __ip_append_data(sk, fl4, &sk->sk_write_queue, &inet->cork.base, getfrag, 1121 from, length, transhdrlen, flags); 1122 } 1123 1124 ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page, 1125 int offset, size_t size, int flags) 1126 { 1127 struct inet_sock *inet = inet_sk(sk); 1128 struct sk_buff *skb; 1129 struct rtable *rt; 1130 struct ip_options *opt = NULL; 1131 struct inet_cork *cork; 1132 int hh_len; 1133 int mtu; 1134 int len; 1135 int err; 1136 unsigned int maxfraglen, fragheaderlen, fraggap; 1137 1138 if (inet->hdrincl) 1139 return -EPERM; 1140 1141 if (flags&MSG_PROBE) 1142 return 0; 1143 1144 if (skb_queue_empty(&sk->sk_write_queue)) 1145 return -EINVAL; 1146 1147 cork = &inet->cork.base; 1148 rt = (struct rtable *)cork->dst; 1149 if (cork->flags & IPCORK_OPT) 1150 opt = cork->opt; 1151 1152 if (!(rt->dst.dev->features&NETIF_F_SG)) 1153 return -EOPNOTSUPP; 1154 1155 hh_len = LL_RESERVED_SPACE(rt->dst.dev); 1156 mtu = cork->fragsize; 1157 1158 fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); 1159 maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen; 1160 1161 if (cork->length + size > 0xFFFF - fragheaderlen) { 1162 ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport, mtu); 1163 return -EMSGSIZE; 1164 } 1165 1166 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 1167 return -EINVAL; 1168 1169 cork->length += size; 1170 if ((size + skb->len > mtu) && 1171 (sk->sk_protocol == IPPROTO_UDP) && 1172 (rt->dst.dev->features & NETIF_F_UFO)) { 1173 skb_shinfo(skb)->gso_size = mtu - fragheaderlen; 1174 skb_shinfo(skb)->gso_type = SKB_GSO_UDP; 1175 } 1176 1177 1178 while (size > 0) { 1179 int i; 1180 1181 if (skb_is_gso(skb)) 1182 len = size; 1183 else { 1184 1185 /* Check if the remaining data fits into current packet. */ 1186 len = mtu - skb->len; 1187 if (len < size) 1188 len = maxfraglen - skb->len; 1189 } 1190 if (len <= 0) { 1191 struct sk_buff *skb_prev; 1192 int alloclen; 1193 1194 skb_prev = skb; 1195 fraggap = skb_prev->len - maxfraglen; 1196 1197 alloclen = fragheaderlen + hh_len + fraggap + 15; 1198 skb = sock_wmalloc(sk, alloclen, 1, sk->sk_allocation); 1199 if (unlikely(!skb)) { 1200 err = -ENOBUFS; 1201 goto error; 1202 } 1203 1204 /* 1205 * Fill in the control structures 1206 */ 1207 skb->ip_summed = CHECKSUM_NONE; 1208 skb->csum = 0; 1209 skb_reserve(skb, hh_len); 1210 1211 /* 1212 * Find where to start putting bytes. 1213 */ 1214 skb_put(skb, fragheaderlen + fraggap); 1215 skb_reset_network_header(skb); 1216 skb->transport_header = (skb->network_header + 1217 fragheaderlen); 1218 if (fraggap) { 1219 skb->csum = skb_copy_and_csum_bits(skb_prev, 1220 maxfraglen, 1221 skb_transport_header(skb), 1222 fraggap, 0); 1223 skb_prev->csum = csum_sub(skb_prev->csum, 1224 skb->csum); 1225 pskb_trim_unique(skb_prev, maxfraglen); 1226 } 1227 1228 /* 1229 * Put the packet on the pending queue. 1230 */ 1231 __skb_queue_tail(&sk->sk_write_queue, skb); 1232 continue; 1233 } 1234 1235 i = skb_shinfo(skb)->nr_frags; 1236 if (len > size) 1237 len = size; 1238 if (skb_can_coalesce(skb, i, page, offset)) { 1239 skb_frag_size_add(&skb_shinfo(skb)->frags[i-1], len); 1240 } else if (i < MAX_SKB_FRAGS) { 1241 get_page(page); 1242 skb_fill_page_desc(skb, i, page, offset, len); 1243 } else { 1244 err = -EMSGSIZE; 1245 goto error; 1246 } 1247 1248 if (skb->ip_summed == CHECKSUM_NONE) { 1249 __wsum csum; 1250 csum = csum_page(page, offset, len); 1251 skb->csum = csum_block_add(skb->csum, csum, skb->len); 1252 } 1253 1254 skb->len += len; 1255 skb->data_len += len; 1256 skb->truesize += len; 1257 atomic_add(len, &sk->sk_wmem_alloc); 1258 offset += len; 1259 size -= len; 1260 } 1261 return 0; 1262 1263 error: 1264 cork->length -= size; 1265 IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); 1266 return err; 1267 } 1268 1269 static void ip_cork_release(struct inet_cork *cork) 1270 { 1271 cork->flags &= ~IPCORK_OPT; 1272 kfree(cork->opt); 1273 cork->opt = NULL; 1274 dst_release(cork->dst); 1275 cork->dst = NULL; 1276 } 1277 1278 /* 1279 * Combined all pending IP fragments on the socket as one IP datagram 1280 * and push them out. 1281 */ 1282 struct sk_buff *__ip_make_skb(struct sock *sk, 1283 struct flowi4 *fl4, 1284 struct sk_buff_head *queue, 1285 struct inet_cork *cork) 1286 { 1287 struct sk_buff *skb, *tmp_skb; 1288 struct sk_buff **tail_skb; 1289 struct inet_sock *inet = inet_sk(sk); 1290 struct net *net = sock_net(sk); 1291 struct ip_options *opt = NULL; 1292 struct rtable *rt = (struct rtable *)cork->dst; 1293 struct iphdr *iph; 1294 __be16 df = 0; 1295 __u8 ttl; 1296 1297 if ((skb = __skb_dequeue(queue)) == NULL) 1298 goto out; 1299 tail_skb = &(skb_shinfo(skb)->frag_list); 1300 1301 /* move skb->data to ip header from ext header */ 1302 if (skb->data < skb_network_header(skb)) 1303 __skb_pull(skb, skb_network_offset(skb)); 1304 while ((tmp_skb = __skb_dequeue(queue)) != NULL) { 1305 __skb_pull(tmp_skb, skb_network_header_len(skb)); 1306 *tail_skb = tmp_skb; 1307 tail_skb = &(tmp_skb->next); 1308 skb->len += tmp_skb->len; 1309 skb->data_len += tmp_skb->len; 1310 skb->truesize += tmp_skb->truesize; 1311 tmp_skb->destructor = NULL; 1312 tmp_skb->sk = NULL; 1313 } 1314 1315 /* Unless user demanded real pmtu discovery (IP_PMTUDISC_DO), we allow 1316 * to fragment the frame generated here. No matter, what transforms 1317 * how transforms change size of the packet, it will come out. 1318 */ 1319 if (inet->pmtudisc < IP_PMTUDISC_DO) 1320 skb->local_df = 1; 1321 1322 /* DF bit is set when we want to see DF on outgoing frames. 1323 * If local_df is set too, we still allow to fragment this frame 1324 * locally. */ 1325 if (inet->pmtudisc >= IP_PMTUDISC_DO || 1326 (skb->len <= dst_mtu(&rt->dst) && 1327 ip_dont_fragment(sk, &rt->dst))) 1328 df = htons(IP_DF); 1329 1330 if (cork->flags & IPCORK_OPT) 1331 opt = cork->opt; 1332 1333 if (rt->rt_type == RTN_MULTICAST) 1334 ttl = inet->mc_ttl; 1335 else 1336 ttl = ip_select_ttl(inet, &rt->dst); 1337 1338 iph = (struct iphdr *)skb->data; 1339 iph->version = 4; 1340 iph->ihl = 5; 1341 iph->tos = inet->tos; 1342 iph->frag_off = df; 1343 iph->ttl = ttl; 1344 iph->protocol = sk->sk_protocol; 1345 ip_copy_addrs(iph, fl4); 1346 ip_select_ident(iph, &rt->dst, sk); 1347 1348 if (opt) { 1349 iph->ihl += opt->optlen>>2; 1350 ip_options_build(skb, opt, cork->addr, rt, 0); 1351 } 1352 1353 skb->priority = sk->sk_priority; 1354 skb->mark = sk->sk_mark; 1355 /* 1356 * Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec 1357 * on dst refcount 1358 */ 1359 cork->dst = NULL; 1360 skb_dst_set(skb, &rt->dst); 1361 1362 if (iph->protocol == IPPROTO_ICMP) 1363 icmp_out_count(net, ((struct icmphdr *) 1364 skb_transport_header(skb))->type); 1365 1366 ip_cork_release(cork); 1367 out: 1368 return skb; 1369 } 1370 1371 int ip_send_skb(struct net *net, struct sk_buff *skb) 1372 { 1373 int err; 1374 1375 err = ip_local_out(skb); 1376 if (err) { 1377 if (err > 0) 1378 err = net_xmit_errno(err); 1379 if (err) 1380 IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS); 1381 } 1382 1383 return err; 1384 } 1385 1386 int ip_push_pending_frames(struct sock *sk, struct flowi4 *fl4) 1387 { 1388 struct sk_buff *skb; 1389 1390 skb = ip_finish_skb(sk, fl4); 1391 if (!skb) 1392 return 0; 1393 1394 /* Netfilter gets whole the not fragmented skb. */ 1395 return ip_send_skb(sock_net(sk), skb); 1396 } 1397 1398 /* 1399 * Throw away all pending data on the socket. 1400 */ 1401 static void __ip_flush_pending_frames(struct sock *sk, 1402 struct sk_buff_head *queue, 1403 struct inet_cork *cork) 1404 { 1405 struct sk_buff *skb; 1406 1407 while ((skb = __skb_dequeue_tail(queue)) != NULL) 1408 kfree_skb(skb); 1409 1410 ip_cork_release(cork); 1411 } 1412 1413 void ip_flush_pending_frames(struct sock *sk) 1414 { 1415 __ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork.base); 1416 } 1417 1418 struct sk_buff *ip_make_skb(struct sock *sk, 1419 struct flowi4 *fl4, 1420 int getfrag(void *from, char *to, int offset, 1421 int len, int odd, struct sk_buff *skb), 1422 void *from, int length, int transhdrlen, 1423 struct ipcm_cookie *ipc, struct rtable **rtp, 1424 unsigned int flags) 1425 { 1426 struct inet_cork cork; 1427 struct sk_buff_head queue; 1428 int err; 1429 1430 if (flags & MSG_PROBE) 1431 return NULL; 1432 1433 __skb_queue_head_init(&queue); 1434 1435 cork.flags = 0; 1436 cork.addr = 0; 1437 cork.opt = NULL; 1438 err = ip_setup_cork(sk, &cork, ipc, rtp); 1439 if (err) 1440 return ERR_PTR(err); 1441 1442 err = __ip_append_data(sk, fl4, &queue, &cork, getfrag, 1443 from, length, transhdrlen, flags); 1444 if (err) { 1445 __ip_flush_pending_frames(sk, &queue, &cork); 1446 return ERR_PTR(err); 1447 } 1448 1449 return __ip_make_skb(sk, fl4, &queue, &cork); 1450 } 1451 1452 /* 1453 * Fetch data from kernel space and fill in checksum if needed. 1454 */ 1455 static int ip_reply_glue_bits(void *dptr, char *to, int offset, 1456 int len, int odd, struct sk_buff *skb) 1457 { 1458 __wsum csum; 1459 1460 csum = csum_partial_copy_nocheck(dptr+offset, to, len, 0); 1461 skb->csum = csum_block_add(skb->csum, csum, odd); 1462 return 0; 1463 } 1464 1465 /* 1466 * Generic function to send a packet as reply to another packet. 1467 * Used to send some TCP resets/acks so far. 1468 * 1469 * Use a fake percpu inet socket to avoid false sharing and contention. 1470 */ 1471 static DEFINE_PER_CPU(struct inet_sock, unicast_sock) = { 1472 .sk = { 1473 .__sk_common = { 1474 .skc_refcnt = ATOMIC_INIT(1), 1475 }, 1476 .sk_wmem_alloc = ATOMIC_INIT(1), 1477 .sk_allocation = GFP_ATOMIC, 1478 .sk_flags = (1UL << SOCK_USE_WRITE_QUEUE), 1479 }, 1480 .pmtudisc = IP_PMTUDISC_WANT, 1481 .uc_ttl = -1, 1482 }; 1483 1484 void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr, 1485 __be32 saddr, const struct ip_reply_arg *arg, 1486 unsigned int len) 1487 { 1488 struct ip_options_data replyopts; 1489 struct ipcm_cookie ipc; 1490 struct flowi4 fl4; 1491 struct rtable *rt = skb_rtable(skb); 1492 struct sk_buff *nskb; 1493 struct sock *sk; 1494 struct inet_sock *inet; 1495 1496 if (ip_options_echo(&replyopts.opt.opt, skb)) 1497 return; 1498 1499 ipc.addr = daddr; 1500 ipc.opt = NULL; 1501 ipc.tx_flags = 0; 1502 1503 if (replyopts.opt.opt.optlen) { 1504 ipc.opt = &replyopts.opt; 1505 1506 if (replyopts.opt.opt.srr) 1507 daddr = replyopts.opt.opt.faddr; 1508 } 1509 1510 flowi4_init_output(&fl4, arg->bound_dev_if, 0, 1511 RT_TOS(arg->tos), 1512 RT_SCOPE_UNIVERSE, ip_hdr(skb)->protocol, 1513 ip_reply_arg_flowi_flags(arg), 1514 daddr, saddr, 1515 tcp_hdr(skb)->source, tcp_hdr(skb)->dest); 1516 security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); 1517 rt = ip_route_output_key(net, &fl4); 1518 if (IS_ERR(rt)) 1519 return; 1520 1521 inet = &get_cpu_var(unicast_sock); 1522 1523 inet->tos = arg->tos; 1524 sk = &inet->sk; 1525 sk->sk_priority = skb->priority; 1526 sk->sk_protocol = ip_hdr(skb)->protocol; 1527 sk->sk_bound_dev_if = arg->bound_dev_if; 1528 sock_net_set(sk, net); 1529 __skb_queue_head_init(&sk->sk_write_queue); 1530 sk->sk_sndbuf = sysctl_wmem_default; 1531 ip_append_data(sk, &fl4, ip_reply_glue_bits, arg->iov->iov_base, len, 0, 1532 &ipc, &rt, MSG_DONTWAIT); 1533 nskb = skb_peek(&sk->sk_write_queue); 1534 if (nskb) { 1535 if (arg->csumoffset >= 0) 1536 *((__sum16 *)skb_transport_header(nskb) + 1537 arg->csumoffset) = csum_fold(csum_add(nskb->csum, 1538 arg->csum)); 1539 nskb->ip_summed = CHECKSUM_NONE; 1540 skb_orphan(nskb); 1541 skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb)); 1542 ip_push_pending_frames(sk, &fl4); 1543 } 1544 1545 put_cpu_var(unicast_sock); 1546 1547 ip_rt_put(rt); 1548 } 1549 1550 void __init ip_init(void) 1551 { 1552 ip_rt_init(); 1553 inet_initpeers(); 1554 1555 #if defined(CONFIG_IP_MULTICAST) && defined(CONFIG_PROC_FS) 1556 igmp_mc_proc_init(); 1557 #endif 1558 } 1559